What is hi-res?

Your coworker asks for a photo, so you quickly email him the one from the web. Moments later, he replies back: “Do you have that in hi-res?”

Does it matter?

Yes; he’s not just being picky. There really is a difference between lo- and hi-res. It can determine whether your company logo looks fuzzy vs. crystal clear. In order to understand when a hi-res image is a must (such as for printing and enlarging), let’s go into what hi-res is in the first place.

You are my density

Hi-res stands for high resolution, or denser image quality. Images are made of tiny pixels (picture elements), or squares of color. You usually don’t notice individual pixels because they all blend together to form the picture that you recognize. But they’re there. You can see pixels when you zoom in really closely to a picture, or if you try to enlarge an image beyond what it can handle.

The lo-res image on the right looks great at its normal size (100%), but when we zoom in, it looks choppy. You can see why enlarging lo-res images gives blurry results.

This look is called “pixelated” because you can distinguish each pixel, in a block pattern. Those of us who pre-date smartphones might recall this distinctive, low-tech aesthetic from back in the day. Ah, the memories (retro video games, anyone?).

Early video games looked pixelated because they used minimal colors on purpose to preserve memory and processing power. Today, we usually only see pixelated images when images are enlarged or zoomed-in too much, or printed from a lo-res file.

Count your pixels

Lo-res images have around 72-pixels, or squares of color, per inch. This makes them great for the web, because that’s all your computer screen will display, anyhow. Plus, they are very lightweight (fewer pixels), so they help websites load quickly.

Hi-res images are at least 300 pixels per inch (ppi). This resolution makes for good print quality, and is pretty much a requirement for anything that you want hard copies of, especially to represent your brand or other important printed materials.

Prevent printing regrets (because ink is expensive)! Use hi-res photos for sharp prints and to prevent jagged lines. Hint: Make sure your phone-camera is taking a high enough resolution to look good when printed.

Is my image hi- or lo-res?

Just because it looks good on your computer screen doesn’t mean it’s hi-res. You can’t tell by the length-width dimensions, either. Heavy file size can be a clue, but not in all cases. The best way is to open up the picture in an image program and view the file properties. You don’t need a fancy program to do this; most computers come with a basic image editing program that will do the trick.

Lo-res for web, hi-res for print

This is just a broad overview, but if you take away one thing, it’s that the resolution you want depends on whether you want the file on-screen only, or print.

Resolution also helps you figure out how much you can enlarge a photo. This comes in handy when trying to figure out what size you can print something (4×6? 8×10?) and have it still look good. Rule of thumb: divide the pixel size (dimension) of the image by the resolution (at least 300 ppi) to get the maximum print size in inches. So, if your image is 2,000 pixels in length at 300 ppi, then you can print it up to six inches or so (2,000 divided by 300).

Hi-res files are a great thing. They have more pixels, are heavier, and are great for printing. They’re well worth the storage space and download time, and for making sure your pictures look great beyond your screen.

Want to find out if your image is hi-res? Snagit lets you easily view image resolutions of 28 popular formats, plus you can resize and edit. Get your free trial.

You say that “You can’t tell by the length-width dimensions, either.”, but that’s really all there is. ppi is just a fake number on top of the pixel count to say how it should be printed. If an image is 2000×2000, it is completely irrelevant whether it is 300ppi or 72ppi (or 10,000ppi) — it’s the same size file and will load just as quickly and will look identical.

David

Hmmm…as soon as I get an email from someone asking for a “hi res image” (actually, they usually ask for a “high resolution JPEG”, I know they don’t know what they’re talking about. But worse, they *think* they’re asking for something precise.

As mickmel’s pointed out, PPI isn’t really relevant to the size of the image or its resolution. It’s a characteristic of the output device. A “72ppi” image that’s 1200 pixels wide will print perfectly well up to about 4 inches wide, or fill 2/3 of an HD screen width. “Lo res” in ppi terms, but enough res in reality. Conversely, a “300dpi” image 1200 pixels wide will have obvious pixelation if it’s printed to a full page.

Sorry to be negative Dayna, but I think this article needs a rewrite (well, a rethink).

If you think that ‘resolution’, as commonly used, is a measure of image quality the consider the following.
I capture a 510 x 406 pixel screen image in Snagit and there are 207060 pixel in the image
The Editor says resolution is 102 dpi

I resize the image (grab handles) to 358 x 260 and there are now 93080 pixels in the same image. 113980 pixels, (207060 – 93080), have been thrown away but the Editor still says resolution is 102 dpi.

I resize the 510 x 406 image to 621 x 440, and now I have added 66180 pixels to the image that weren’t there before. The Editor still says resolution is 102 dpi !!

It’s an uncomfortable fact that much of what you read in computer graphics books
and articles is wrong.

martin flaxman

Richard, what are those square of colour called then?

Doug Brown

Dayna, this blog posting on hi-res was entertaining and useful, regardless of the ongoing discussion on poi, dpi, resolution, etc. I do have a comment about SnagIt’s “resizing” feature though (on my Mac).

I often copy captured images into Outlook emails. At 100% (original capture size) they are often too big. I tried using the Resizing command to reduce their size while keep the ratios, often to 65%. When these resized images are pasted into my Outlook email, they LOSE SUBSTANTIAL RESOLUTION. I assume that this means that the images are not just being reduced in presentation size but also down-sampled. The result is very poor resolution. My workaround has been to paste the larger, original captured image, and then use grab handles in the object pasted into my emails to make them smaller. I would love it if you could really explain what the Resize command does, as resolution seems sacrificed.

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